doc: add gyp maintain info

PR-URL: https://github.com/nodejs/node/pull/37765


Reviewed-By: Ujjwal Sharma <ryzokuken@disroot.org>
Reviewed-By: Richard Lau <rlau@redhat.com>
Reviewed-By: Mary Marchini <oss@mmarchini.me>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>